A2UI: A Protocol for Agent-Driven Interfaces

(emphasis mine)

Sounds like agents are suddenly able to do what developers have failed at for decades: Writing platform-independent UIs. Maybe this works for simple use cases but beyond that I'm skeptical.

Some examples from the documentation: { "id": "settings-tabs", "component": { "Tabs": { "tabItems": [ {"title": {"literalString": "General"}, "child": "general-settings"}, {"title": {"literalString": "Privacy"}, "child": "privacy-settings"}, {"title": {"literalString": "Advanced"}, "child": "advanced-settings"} ] } } }

{ "id": "email-input", "component": { "TextField": { "label": {"literalString": "Email Address"}, "text": {"path": "/user/email"}, "textFieldType": "shortText" } } }

How many more variants are we introducing to solve the same problem. Sounds like a lot of wasted manhours to me.

The genuinely interesting bit here is the security boundary: agents can only speak in terms of a vetted component catalog, and the client owns execution. If you get that right, you can swap the agent for a rules engine or a human operator and keep the same protocol. My guess is the spec that wins won’t be the one with the coolest demos, but the one boring enough that a product team can live with it for 5-10 years.

1. Establish SSE connection

... user event

7. send updates over origin SSE connection

So the client is required to maintain an SSE capable connection for the entire chat session? What if my network drops or I switch to another agent?

Seems an onerous requirement to maintain a connection for the life-time of a session, which can span days (as some people have told us they have done with agents)

Feels good to have been on the money, but I'm also glad I didn't start a project only to be harpooned by Google straight away

What scares me is that even without arbitrary code generation, there's the potential for hallucinations and prompt injection to hit hard if a solution like this isn't sandboxed properly. An automatically generated "confirm purchase" button like in the shown example is... probably something I'd not make entirely unsupervised just yet.

However, I'm happy it's happening because you don't need an LLM to use the protocol.

It is simple, effective and feels more native to me than some rigid data structure designed for very specific use-cases that may not fit well into your own problem.

Honestly, we should think of Emacs when working with LLMs and kind of try to apply the same philosophy. I am not a fan of Emacs per-se but the parallels are there. Everything is a file and everything is a text in a buffer. The text can be rendered in various ways depending on the consumer.

This is also the philosophy that we use in our own product and it works remarkably well for diverse set of customers. I have not encountered anything that cannot be modelled in this way. It is simple, effective and it allows for a great degree of flexibility when things are not going as well as planned. It works well with streaming too (streaming parsers are not so difficult to do with simple text structures and we have been doing this for ages) and LLMs are trained very well how to produce this type of output - vs anything custom that has not been seen or adopted yet by anyone.

Besides, given that LLMs are getting good at coding and the browser can render iframes in seamless mode, a better and more flexible approach would be to use HTML, CSS and JavaScript instead of what Slack has been doing for ages with their block kit API which we know is very rigid and frustrating to work with. I get why you might want to have a data structures for UI in order to cover CLI tools as well but at the end of the day browsers and clis are completely different things and I don not believe you can meaningfully make it work for both of them unless you are also prepared to dumb it down and target only the lowest common dominator.

Why the hell would anyone want this? Why on earth would you trust an LLM to output a UI? You're just asking for security bugs, UI impersonation attacks, terrible usability, and more. This is a nightmare.

Yes yes we claim the user doesn’t know what they want. I think that’s largely used as an excuse to avoid rethinking how things should meet the users needs and keep status quo where people are made to rely on systems and walled gardens. The goal of this article is UIs should work better for the user. What better way then to let them imagine (or even nudge them with example actions, buttons, text to click to render specific views) in the UI! I’ve been wanting to build something where I just ask in English from options I know I have or otherwise play and hit edges to discover what’s possible and not.

Anyone else thinking along this direction or think I’m missing something obvious here?

The real question: do UIs even make sense for agents? Like the whole point of a UI is to expose functionality to humans with constraints (screens, mice, attention). Agents don't have those constraints. They can read JSON, call APIs directly, parse docs. Why are we building them middleware to click buttons?

I think this makes sense as a transition layer while we figure out what agent-native architecture looks like. But long-term it's probably training wheels.

Will include this in my https://hackernewsai.com/ newsletter.